Direct cumulant lattice Boltzmann simulations of transitional flow in gyroidal structures including experimental validation

In this work, transitional flow characteristics in gyroidal structures are investigated. For specified flow rates corresponding to a range of Reynolds numbers from 400 to 7000, the pressure drop between inlet and outlet is determined. The experimentally obtained pressure drops are computed numerically with the cumulant lattice Boltzmann method which serves as a solver for the weakly compressible flow. Different grid resolutions are used for the simulations in order to investigate grid convergence. In order to create an accurate geometric representation of the setup, we use a newly developed formalism to describe gyroids with finite thickness based on an implicit volume representation. This representation avoids the expensive and inaccurate triangulation of the gyroid structure. Consequently, it avoids the problems encountered with mesh -based representations by providing a compact, local, and therefore inherently parallel representation for geometric computations such as classification of nodes and the computation of subgrid distances.